I would build one, put one speaker in it, and try it out. If you are not happy with it, there's not much point in doing anything more until you find out why. One box with one speaker will have to be very close to what your looking for, because a second speaker or a second box just isn't going to add that much, a little - yes, but not a huge difference. (The one exception might be 2 boxes out of phase...this creates null spots, but also "super" spots. If the super spot is where the driver sits, they - yes, a 2nd box could add a lot - but you pay for it).

Your driver specs are pretty close to a driver I used with very good success in a deathbox12. Funny thing about that deathbox was that it sounded "ok" in my car and in a friends car but sounded extraordinary in a friends van, better than anything else ever tried in that vehicle. Haven't seen the deathbox since...

My questions was not if i would be happy with it, I am sure I will be. I only have them in a generic 1.25 sq ft sealed square box now. They came in about a 1 sq ft sealed box with no polyfill, they were lets say not too impressive, Ok they down right just sucked. but I only paid 35 bucks for them off criegs list and I really like JBL, They really came alive once I dropped them in there new box. They sound not too bad. but still not quiet what I am looking for. What I really want is somthing that has really good SQ and can really put out the SPL when I want it to.

What I really wanted to know is, In your infinite wisdom what would be a better choice to clamshell 2 speakers in one box or have 2 separate boxes.

So why did it just sound "ok"? What is the price you speak of?

well I get my MDF today so I get to start on my build. I will document and post how it goes.

I can only see a benefit to clamshelling if using cheap drivers that perform with gross differences in their ability to follow a waveform's positive and negative swings or exhibit bad "linearity" in one way or another.

Since none of us want to use drivers like that anyway, the point may be moot.(I know that there could be other benefits, but in an attempt to be succinct, generally, I say, skip it.)

The only other reason to clamshell is if you have way too much amplifier power and want to divide it in half across your drivers. Quite unlikely, I expect.